GoalZero Rock-Out Speakers - Rechargeable MP3 SpeakerShare Music Anywhere with GoalZero Rock-Out Speakers - Rechargeable MP3 Speaker. It is a lightweight set of speakers that comes in a wooden sound box for fuller sound, but it has a funky carrying case that makes it easy to take on the trail or to the beach and comes in 6 different colors. It is weather resistant and has a long battery life, up to 20 hours so it should last all day. Hit the trails, water or office and share hours of high quality sound with fellow trekkers The Rock-Out pumps sound from your iPod, mp3, mp4 and other audio devices through the GoalZero Rock-Out Speakers - Rechargeable MP3 Speaker.